Connect the dots: understanding the SightGlass Vision DOT spectacle lens

New innovations in myopia control treatments have increased options available to the clinician. Spectacle lenses can be a first line choice for myopia management as they provide both myopia correction and control, and can be suitable for a wide range of children. The SightGlass Vision DOT lenses are a new myopia control design with hot-off-the-press clinical trial data showing a robust myopia control effect. They are underpinned by a different mechanism and theory of myopia control than other designs - based on contrast theory rather than optical defocus theory. This article explores the DOT lens design, and how they work.

The SightGlass Vision company was founded in 2016 to develop this new spectacle lens technology, and since 2021 operates as a joint venture of CooperCompanies and EssilorLuxottica. The spectacle lenses incorporate Diffusion Optics Technology^TM (DOT), whereby thousands of small elements across the lens, shaped as dots, scatter light onto the retina. The small (around 5mm) central section of the lens does not incorporate these dots, providing clear vision and facilitating lens power verification. When worn by a child with myopia, the SightGlass DOT lens appears similar to a regular, single vision lens - see the image below (provided by SightGlass Vision) which shows the aesthetic appearance of the lens on a child's face.

One-year results from an ongoing, multi-site randomized clinical trial have shown that in children aged 6 to 10 years, the DOT 0.2 lens reduced myopia progression by -0.40D (74%) in spherical equivalent refraction and 0.15mm (50%) in axial length compared to a single vision control.¹ This is the first data of its type in younger children aged 6 to 8 years, as the two other novel myopia control spectacle lens designs (DIMS and H.A.L.T. Technology) reported clinical trial results in children aged 8 to 13 years. This is important data as this age group tends to show some of the fastest myopia progression.^2,3

With an excellent safety profile, clinically and cosmetically, the SightGlass DOT 0.2 lenses offer a robust choice for myopia control. The purpose of the dots in the lenses is to reduce the contrast of the image formed on the retina. The lenses are based on the contrast theory as a mechanism of myopia development and progression.

Contrast is an important aspect of the visual experience. It is the ability of the eye to distinguish differences in luminance, which is essential for object recognition.

Contrast theory hypothesises that myopia arises from the amount of retinal stimulation that occurs. High contrast images cause high retinal stimulation; low contrast images cause low retinal stimulation. It is thought that overstimulation of the retina from high contrast is associated with overstimulation of eye growth, thus instigating myopia progression.⁴

Gene studies investigating heritable forms of high myopia support the theory. In X-linked myopia conditions, genetic mutations responsible for high myopia were found in genes encoding cone photopigments. Cone photoreceptors are responsible for fine detail vision; it was discovered that these mutations in certain cones created a mosaic of functional cones adjacent to dysfunctional cones (almost devoid of photopigment), leading to a disparity in retinal signalling; that is, the retina will signal high contrast even in the absence of high contrast visual stimuli.⁴ Greater photopigment deficit is correlated with higher degrees of myopia.⁵

This high retinal contrast is thought to instigate axial elongation. While this theory was originally developed in investigation of very high, heritable forms of myopia, what of non-heritable forms? Research in Norway, which has a low prevalence of myopia, has shown a correlation between 'common myopia' (eg. non-syndromic and lower in magnitude) and alterations in the ratios of long (L) and middle (M) wavelength cones. Varied genetic expressions of the L or M opsin signalling indicate the role of contrast differences in adjacent cone photoreceptors and myopia.⁶

How could we link retinal contrast and visual environment in our modern surge of myopia prevalence? The well-established protective impact of time spent outdoors⁷ implies that time spent indoors promotes myopia development. In addition to luminance differences, it has been suggested that spatial characteristics of indoor and outdoor scenes, and how these signal retinal imaging, may play a role.⁸ Read more in our article on The Contrast Theory: a new approach in myopia.

The SightGlass DOT lens is designed to slightly reduce and modulate (ie. 'even out') retinal contrast by scattering light, in order to lower the signal for eye elongation and myopia progression.¹

The treatment zone of DOT lenses incorporate microdots that softly disperse any light that passes through it, thereby modulating contrast. These microscopic diffusers are about one tenth of a millimetre wide. The microdots are not designed to produce peripheral defocus: the main goal is to slightly lower retinal contrast irrespective of viewing distance.¹

These microdots encompass most of the lens, except for a small portion (around 5mm diameter) in front of the pupil that provides uninterrupted, clear vision. The central clear portion is a useful aid for low contrast fine detail vision, and also aids the practitioner to measure the lens power. This does not mean that the wearer is only given a small portion of lens to look through: in fact, the wearer is still able to look through any portion of the lens. The treatment zone of microdots does not appear to affect vision to the point that it is not useable: both central and peripheral vision are functional despite the microdots. When looking through the treatment zone, the images have a softer appearance without losing detail. According to participant and parent questionnaires about the tolerability of the lenses, children that wore the lenses adapted well to them.⁹ Peer reviewed literature on visual acuity and visual function outcomes with the DOT 0.2 lenses is yet to be published.

The Control of myopia using diffusion optics spectacle lenses (CYPRESS) clinical trial involved 256 children aged 6 to 10 years of age with a spherical equivalent refraction (SER) of -0.75DS to -4.50DS. Children were encouraged to wear their spectacles for at least 10 hours per day, every day.

After one year, the children wearing the DOT 0.2 lenses showed 0.15mm axial length growth compared to 0.30mm in the control group, representing a 50% axial length control effect. Refraction progressed only -0.14D in the treatment group, compared to -0.54D in the control group - a 74% control effect. In the younger age group 6 to 7 years, for whom this is the first data of its type, refractive change was only -0.19D over one year compared to -0.75D in the age-matched control group.¹

No ocular adverse events in the clinical trial were related to the spectacle lenses. Around 13% of both DOT 0.2 and control group wearers reported 'device deficiencies', with most being 'issue with frame' and only 4.5% of the DOT 0.2 lens reported 'issue with lens'.¹

The 3-year clinical trial has been completed and reported at the American Academy of Optometry meeting in late 2022. The extension study is ongoing to ultimately report on axial length and refractive control data beyond three years.¹⁰

• The SightGlass DOT Lens - Q&A with Dr Sherman Tung

• The Contrast Theory: A New Approach In Understanding Myopia

• Science Summary: Myopia Control With Diffusion Optics Technology: Preliminary Results From The CYPRESS Study

Important note: DOT lenses are currently not available in the US but are available in selected countries outside the US.